This invention relates to fluid compressors and, more particularly, to improvements of refrigerant compressors of the wobble type in which pistons are reciprocated by a wobble plate driven by a rotor which is secured on a drive shaft.
A wobble type compressor of this type is described in U.S. Pat. No. 3,552,886 (which is reissued under U.S. Pat. No. Re. 27,844). In such a compressor, the rotor is formed in the form of a wedge and is sandwiched between the wobble plate and a front plate which rotatably supports the drive shaft. The wobble type compressor is small in volume and is suitable for refrigeration systems of the automotive or mobile type.
The compressor shown in the above described U.S. patent is provided with two anti-friction or roller thrust bearing assemblies. One of the thrust bearing assemblies is disposed between an end plate of the compressor housing and the rotor to take up thrust load on the rotor as will appear. And the other bearing assembly is disposed between the rotor and the wobble plate. Accordingly a frictionless driving of the wobble plate is provided. When the compressor is driven by an engine system mounted on the automobile, it is not avoidable that the rotating speed of the drive shaft varies momentarily. Accordingly, the race members of the thrust bearing assemblies readily slip and rotationally move on seated parts, which parts, therefore, are worn out.
Furthermore, by the rotation of the rolling element or needle roller and the, cage assemblies of the anti-friction thrust bearing assemblies during the operation of the compressor, the rolling element cage assemblies wear out parts which contact therewith.
Accordingly, it is required to use hard materials such as steel as the end plate, the rotor member and the wobble plate member. But this increases the weight of the compressor.